Vinylchlorosilanes, in particular vinyltrichlorosilane, are useful products which are widely used in industry. For instance, they are used for sizing of glass fabrics and in the production of vinylpolysiloxanes.
German Patent No. 936,445, German Offenlegungsschrift No. 22 10 189 and particularly German Patent No. 20 02 258 disclose that when mixtures of vinyl chloride and chlorosilanes and in particular mixtures of vinyl chloride and trichlorosilane are passed through appropriately heated tubes made of ceramics, glass or iron, industrially acceptable yields of vinylchlorosilanes or vinyltrichlorosilane are obtained. In the case of vinyltrichlorosilane, yields of about 50 to 98% are reached, depending on the ratio of the starting components to one another, based on the conversion of the component which is used in less than a stoichiometric amount. These results are achieved when reaction tubes having an internal diameter of 2.5 to 3.5 cm and a length of 122 to 150 cm, mean residence times of the reactants of 0.2 to 20 seconds, reaction temperatures of 400.degree. to 750.degree. C. and pressures of 1 to 3 bar are used. Depending upon the choice of dimensions of the reactor tube and on the reaction parameters, 0.8 to 3.2 tons per month of vinyltrichlorosilane can be produced in such reactors.
The sudden increase in the demand for vinylchlorosilanes, especially for vinyltrichlorosilane, made it necessary to try to increase the output per reaction unit.
According to German Patent No. 20 02 258, particularly good yields are obtained if the internal diameter of the reactor is about 35 mm. In an attempt to increase the output of the unit by enlarging the internal diameter of the reactor, and thus to increase the throughput per unit time, it has been determined that, although a limited increase in the output of the reactor unit occurs up to an enlargement of the internal diameter to 50 mm, this is far from proportional to the increase in the cross-sectional area of the reactor tube. With a further enlargement of the internal diameter of the reactor tube, even a decrease in the achievable output of vinyltrichlorosilane relative to the cross-sectional area of the reactor occurs. Consequently, it is impossible to increase the space-time yield of vinylchlorosilanes in the known tube reactors by enlarging the internal diameter of the reactor tube.